1994 Mercedes E320 wagon alternator removal
 

I am about to take the alternator, prior to taking it to the auto store for testing, off the 1994 E320 wagon. Can the alternator be remove without taking the serpentine belt off? If I just loosen the tension bolt and remove the two bolts connecting the alternator, should that work and be able to remove the alternator?

There is no tension bolt on an m104. You will need to loosen the belt by means of the belt tensioner, which you can do by putting a 15mm socket on to it and pushing your wrench clockwise. The pulley is located just under the water pump pulley. You can leave the belt hanging there I guess, but it needs to come off the alternator in order for you to remove it.

i have had the tensioner on both a 94 and 95... you can get the alternator off without loosening the bolt.....but you can't get it on..
on my 104's... the big center bolt is an allen head....loosen it good... and then loosen the 13mm protruding bolt just enough to get the belt off....

i just did the alternator on my cab.... twice.... first one was bad....

i tried to do the first one without loosening the tensioner and this is what learned

Lee,
This forum taught me how to do this on the M103, and it works - no need to touch the tensioner. Can this also be done on the M104 -is the alternator bracket/mount the same as the M103?

same.... i had to do an alternator on a 103, too... if you can pull it off more power to you... seems like i used a long screwdriver to leverage the belt over the the power steering pulley

Alternator
 

Before you take off the alternator. If it is like the one in my 91 300e you can remove the regulator and brushes with the alternator in place. When my alternator failed the abs and srs light came on then the car died shortly thereafter. The battery light never came on. The brushes wore down to the point where they were no longer making contact and the alternator stops charging. When battery voltage drops to about 10 or so volts the abs and airbag circuits light up because of low voltage. I think the brushes are part of the circuit to light the battery light and since they are no longer making contact the light won't light up.

alternator is working after replacing the brushes. Having problem with belt tensioner
 

Just a follow up. I took the alternator to a alternator/generator shop to test the alternator. No charging, even I replaced with a new voltage regulator. I showed the old voltage regulator to the person in charge. He looked at the alternator and saw the contact points was not in touch with the voltage regulator. So he took a screw driver and did some bending on the contact points. When he tested the alternator again, it works!!! It seemed that when I replaced the voltage regulator with a new one, I must have jammed the brushes to get in the alternator. In any event, the alternator is working fine. He did charge me $2 for the labor and the time. I did not have the cash then to pay him at the time, since I used my credit/debit cards for payments. He said don't worry just come back again and pay him in cash. WOW!! Really nice guy to work with.

After that, I went to autozone just to test it again. The salesperson said the alternator was not charging.!!! How strange. So I went home and put the alternator in the car. Connect the battery, turn on the ignition, not starting, and sure enough
all the instrument lights in the cluster panel were on. However, when I start to turn the tensioner adjuster rod, nothing was turning to tighten the belt (after I already line up the serpentine belt). There were two nuts above the metal hole where the tensioner adjuster rod goes through. I started to turn righty righty and no movement from the tensioner to tighten up the belt. So I got a new adjuster rod with the long nut that goes on top of the adjuster rod. I took off the new adjuster nut from the new rod and put in the old adjuster rod to see if the tensioner will move to tighten up the belt. No movement on the tensioner. In fact, the long nut broke the thread to the rod, leaving the rest of the thread intact inside the adjuster rod nut.

It looks like I need to replace the tensioner adjuster rod completely with the new one I already bought. I also took the adjuster nut to a fix it shop to have the old thread remove from the nut. If that cannot be done, then I have to get another new adjuster rod nut.

Once I get the adjuster nut taken care of, how do I remove the tensioner belt adjuster rod from engine before I put in a new one? some say to remove the radiator and the water pump to get to the tensioner plate out?
Any other items that need to be remove in order to have room to remove the tensioner adjuster rod? Do I need to replace parts relating to the tensioner adjuster rod? Any comments or feedback is greatly appreciated

i have owned 6 124's.... i have only busted one radiator....and that's because i took a short cut and thought I could get some parts out cleanly.

taking the radiator out is a piece of cake...

with the tensioner.... you have to loosen all the pulley bolts first.. the you have to use the special tool...usually homemade... to lock the fan pulley...and get that off.....

this all just takes time and patience...not that difficult... the tensioner will just slip out between where the pulley were....

this will happen to every 124 somewhere between 125k and 175k....

if you think about it...the parts are dirt cheap... it just takes tools, patience and time.

dmorgan, when adjusting that style tensioner you must loosen (a turn or two) the allen head bolt in the center of the tensioner, otherwise you destroy the tensioner rod threads ... as you experienced. Recommend buying an entire new tensioner assembly since they fail as they get older. Get a new tensioner shock absorber also. As Lee mentions removal/replacement is quite involved and tedious. Best to clean the area thoroughly so you can see all the bolt heads and positioning of components. Take particular note of the orientation of the tensioner parts because if you install them incorrectly the tensioner will not function properly. Allow plenty of time for the removal/replacement and have patience.

Tension adjuster rod is replaced and works great!!!
 

To all who gave me comments, advice and feedback, I was abled to get a hold of a very good friend who knows how to repaired these type of things. He did not have to remove the water pump or power steering pump as some of the people suggested to get access to the tensioner and the adjuster rod. I saw parts of what he did but did not want to bother him. All in all, it took him about 3 hours to remove the tension rod adjuster and replace with a new one. He must have quite a few tricks up in his sieves. Also, the new adjuster rod nut in which the threads from the old adjuster rod nut were removed. I saw the old adjuster tensioner rod and it was ugly. Broke in half and the rod itself was bent, too! Boy, I cannot tell how much I am so relieved with the right people to help out on the Mercedes. The Mercedes e320 station wagon runs a lot better and smoother like a new car. I am impressed with all of you out there taking the time reading and writing helpful hints and comments. Thank you all and you guys rock!!!